In this section we analyze bounds on the low-energy expansion of the elastic amplitude \(f(s,u)\)  using the techniques of Ref. [1]} and [2]}, [3]}.See also Ref. [4]} for a closely related discussion. We focus on couplings of the same dimensionality and derive two-sided bounds on them by explicitly identifying the facets of the relevant polytopes and then taking their crossing-symmetric section.
